The development of information retrieval systems has predominantly focused on improving the overall quality of the search results presented to the user. The quality of the results has typically been measured in terms of precision, recall, or other quantifiable measures of performance. Information retrieval systems, or ‘search engines’ in the context of the Internet and World Wide Web, use a wide variety of techniques to improve the quality and usefulness of the search results. These techniques address every possible aspect of search engine design, from the basic indexing algorithms and document representation, through query analysis and modification, to relevance ranking and result presentation, methodologies too numerous to fully catalog here.
Regardless of the particular implementation technique—the fundamental architectural assumption for search engines has that the search engine's operational model is fixed and non-alterable by entities external to the system itself. That is, the search engine operates essentially as a “black box”, which receives a search query, processes the query using a complex, yet preprogrammed search algorithm and relevance ranking model, and provides the search results. Even where the details of the search algorithm are publicly disclosed, the search engine itself still operates only according to this algorithm, and nothing more.
An inherent problem in the design of search engines is that the relevance of search results to a particular user depends on factors that are highly dependent on the user's intent in conducting the search—that is why they are conducting the search—as well as the user's circumstances—the facts pertaining to the user's information need. Thus, given the same query by two different users, a given set of search results can be relevant to one user and irrelevant to another, entirely because of the different intent and information needs. Most attempts at solving the problem of inferring a user's intent typically depend on relatively weak indicators, such as static user preferences, or predefined methods of query reformulation that are nothing more than educated guesses about what the user is interested in based on the query terms. Approaches such as these cannot fully capture user intent because such intent is itself highly variable and dependent on numerous situational facts that cannot be extrapolated from typical query terms.
Consider, for example a user query for “Canon Digital Rebel”, which is the name of a currently popular digital camera. From the query alone it is impossible to determine the user's intent, for example, whether the user is interested in purchasing such a camera, or whether the user owns this camera already and needs technical support, or whether the user is interested in comparing the camera with competitive offerings, or whether the user is interested in learning to use this camera. That is, the user's situational facts (e.g., whether or not they own the camera currently, their level of expertise in the subject area), and their information need (e.g., the type, form, level of detail, of the request information) cannot themselves be reliably determined by either analysis of query terms, or resort to previously stored preference data about the user.
Another method of inferring intent is the tracking and analysis of prior user queries to build a model of the user's interests. Thus, some search engines store search queries by individual users, and then attempt to determine the user's interests based on frequency of key words appearing in the search queries, as well as which search results the user accesses. One problem with this approach is the assumption that queries accurately reflect a user's interests, either short term or long term. Another is that it assumes that there is a direct and identifiable relationship between a given information need, say shopping for a digital camera, and the particular query terms used to find information relevant to that need. That assumption however is incorrect, as the same query terms can be used by the same (or different users) having quite different information needs.
Perhaps because in part of the inability of contemporary search engines to consistently find information that satisfies the user's information need, and not merely the user's query terms, users frequently turn to websites that offer highly specialized information about particular topics. These websites are typically constructed by individuals, groups, or organizations that have expertise in the particular subject area (e.g., knowledge about digital cameras). Such sites—referred to herein as vertical content sites—often include specifically created content that provides in-depth information about the topic, as well organized collections of links to other related sources of information. For example, a website devoted to digital cameras typically includes product reviews, guidance on how to purchase a digital camera, as well as links to camera manufacturer's sites, price comparison engines, other sources of expert opinion and the like. In addition, the domain experts often have considerable knowledge about which other resources available on the internet are of value and which are not. Using his or her expertise, the content developer can at best structure the site content to address the variety of different information needs of users.
However, while such vertical content sites provide extensive useful information that the user can access to address a particular current information need, the problem remains that when the user returns to a general search engine to further search for relevant information, none of the expertise provided by the vertical content site is made available to the search engine. Many vertical content sites provide a search field from which the user can access a general search engine. This field is merely used to pass a user's search query back to the general search engine. However, none of the expertise that is expressed in the vertical content site is directly available to the general search engine as part of the user's query in order to provide more meaningful search results. The expert content developer has no formal, programmatic way of passing information to the general search engine that expresses their expertise in their particular knowledge site.
In other words, there are no contemporary search engines that can be programmed by external entities—such as vertical content sites—during the search process itself, in way that can enhance the search process with the expertise of the content developer of the vertical content site.